SSANGYONG Rexton 2004 Service Manual page 755

GENERAL
SUMMARY
The aim of the ABS is to mmaintain steerability and driving stability and to take the burden off the driver. If the stopping
distance is shorter on some road surfaces (carriageway conditions), this is a gift of physics and not a development aim.
ABS is a device which senses that one or more of the wheels are locking up during braking. It monitors the rotational
speeds of the wheels and reduces hydraulic pressure to any wheel it senses locking up. It is controlled by both
mechanical and electronic components. When you apply the brakes, the ABS will regulate the flow of brake fluid being
delivered to the brake calipers. By the use of electronic computers, the brakes rapidly alternate (at a rate of 30 times per
second) from full pressure to full release.
DRIVING PHYSICS
To give you a better understanding of the tasks and functions of ABS, we will first look at the physics principles.
The Stopping Distance
The stopping distance depends on the vehicle weight and initial speed when braking starts. This also applies for vehicle
with ABS, where ABS always tries to set an optimum brake force on each wheel. As great forces are exerted between
the tires and the carriageway when braking, even with ABS the wheels may scream and rubber is left on the road. With
an ABS skid mark one may be able to clearly recognize the tire profile. The skid mark of an ABS vehicle does not
however leave any hint of the speed of the vehicle in the case of an accident, as it can only be clearly drawn at the start
of braking.
Brake Force On A Wheel
The maximum possible brake force on a wheel depends on the wheel load and the adhesion coefficient between tire and
carriageway. With a low adhesion coefficient the brake force, which can be obtained is very low. You are bound to know
the result already from driving on winter roads. With a high adhesion coefficient on a dry road, the brake force, which can
be obtained, is considerably higher. The brake force, which can be obtained, can be calculated from below formula:
Maximum brake force
FB = Wheel load F x Adhesion coefficient
max R
The braking process cannot be described sufficiently accu-
rately with the brake forces calculated. The values calculated
only apply if the wheel is not locked. In the case of a locking
wheel, the static friction turns into lower sliding friction, with
the result that the stopping distance is increased. This loss of
friction is termed "slip" in specialist literature.
ABS
REXTON SM - 2004.4
mh
Brake force on a wheel
CHANGED BY
EFFECTIVE DATE
AFFECTED VIN
8E1-3
Y220_8E1001